*2.2.9. Wrong timing of vaccination*

Mostly the vaccines should be done early in the morning or later if it is during summer. The birds feel comfortable during cold hours of the day. As a result, a good response is obtained after vaccination. Otherwise, the chances of vaccine failures are increased in the case of vaccinating birds during the hot hours of the day.

#### *2.2.10. Climatic factors*

The climate variation is a change in climatic parameters (temperature, rainfall, humidity and soil moisture) [23]. Climate change affects both living and nonliving creatures, thus contributing to the health of poultry flocks and may lead to vaccine failure and disease outbreaks.
